KidZone ScienceThe
History of the Polygraph Machine

In 1902 an inadequate lie detector test was invented by a man
named James McKenzie. Later on in the 18th century, 1921, a medical
student named John Larson from the University of California invented
the modern polygraph instrument, which was much more accurate in its
results than the previous machine. Although it recorded several
different physiological responses, it was not as advanced as the
modern polygraph instrument; it measured the subjects pulse rate,
blood pressure and respiratory rate and recorded the information on
a rotating drum of smoke paper. In 1925 Leonarde Keeler refined the
instrument invented by John Larson; instead of using smoke paper to
record changes in the suspects’ reactions, he incorporated ink pens
in order to ensure the efficiency of the machine. In 1938 the
machine was further improved by Keeler. He added another measuring
component, galvanic skin resistance. The polygraph machine continued
to advance
throughout the years; a man named John Reid introduced the idea of
using ‘control questions’ as a means of comparison. After many years
of experimenting with ways to improve the machine, the machine was
finally computerized in 1992, this allowed the machine to record the
results of the test more efficiently.